1. Applied Geomorphology Lecture Notes
By David T. Allison
Geomorphology Lecture Notes: Topographic Maps

2. Topographic Maps Scale (Relational Fraction; Graphical)
Elevation contours (Relative to M.S.L)
Boundary (Latitude & Longitude)
Color (Water bodies, Woodlands, etc.)
Cultural Features (man-made features)
Features of Topographic Maps
Scale (relational fraction RF; Graphical scale in metric and imperial units).
Elevation contours (relative to mean sea level), spot elevations, benchmarks.
Latitude and Longitude boundary (example: 7.5 x 7.5 minute maps at 1:24,000 scale).
Color (Blue=water; green = vegatation; etc.)
Cultural features (buildings, roads, etc.).

3. Scale Relational fraction 1:24,000
1 inch on the map = 24,000 inches in reality
1 inch on the map = 24,000 inches x 1 foot/12 inches
1 inch on the map = 2000 feet
1 inch on the map = 2000 feet x 1 mile/5280 ft
1 inch = miles
Relational Fraction (RF)
Should be conceptualized as a ratio of the paper map to reality.
For example on a 1:24,000 scale map 1 inch on the paper map = 24,000 inches in reality.
From the above starting statement any useful scale may be derrived:
1 inch on the map = 24,000 inches in reality
1 inch on the map = 24,000 inches x 1 foot/12 inches
1 inch on the map = 2000 feet
1 inch on the map = 2000 feet x 1 mile/5280 ft
1 inch = miles

4. Graphical Scale Uses a graphical scale to indicate distances
All topographic maps should have a graphical bar scale that documents the scale of the map. This is especially important when the map is reproduced or projected at a scale different than the original paper map – in whch case the RF will not be correct.
U.S. government maps normally have graphical scales in imperial and metric units.

5. Elevation Contours Contour lines (brown)
Based on aerial photographs analyzed stereographically
Must agree with benchmarks and spot elevations
Contour interval: elevation change between adjacent contours
Hachured contours indicate closed depressions

6. Construction of Topographic Contours
Contours of any parameter use a simple proportionality rule
Contours should “V” in the upstream direction across valleys.
flow 87 80 x x 80 77 x x

7. Topographic contours in 3D

8. Topographic contours in 3D cont.

9. Contours: can delineate geological contacts

10. Topographic Map Boundary
103 30’
103 22’ 30’’
Always consist of lines of latitude and longitude
Contain tick marks of UTM and SPCS on the border
32 15’
32 15’
7.5’ Topographic
Quadrangle border
(1:24,000)
32 7’ 30’’
32 7’ 30’’
103 30’
103 22’ 30’’

11. Topographic Map Colors
Brown: topographic contours
Green: Forest and/or wetlands
White: cleared areas (i.e. pastures, etc.)
Black: Cultural features (buildings, roads)
Red: Land office grid system (Township & Range system); Major road systems
Magenta: Photo-revised areas
Blue: water bodies

12. Topographic Map Examples

13. Map Coordinate Systems
Land Office Grid system (Township & Range)
Universal Transverse Mercator (UTM)
State Plane Coordinate System (SPCS)

14. Land Office Grid System
6 miles
R2W
R1W
R1E
R2E
T2N 6 1 7 12
T1N 18 13
T1S 19 24 30 25
T2S 31 36
State Capital
36 square
miles NW NE
Legal description of location:
NE ¼ , SW ¼, section 22, T2S, R2E SE
Target location

15. Land Office Grid Example:
Benchmark 212:
NW ¼, NE ¼, sec. 36, T3S, R3W